In flight physics unreal

[jwt101]

• KSP version v0.90.705 Beta, Steam
  
• System specifications Windows 7 64-Bit
  

The in flight physics seem all wrong. When using a very simple rocket design (FL-T400, LV-T30), the craft behaves strangely after the fuel has been depleted and the engine shut down. It decends tail-first extremely slowly through the last few thousand feet at <1m/s decent rate (oscillating between 0-5m/s), taking >5mins to pass the last 300m despite zero thrust. When the parachute is deployed decent rate increases immediatly to a more normal 10m/s.

Prior to chute deployment, if the craft is manually pointed nose-down the decent rate accelerates rapidly, which can be converted into a zoom-climb with no thrust.

[BudgetHedgehog]

Well that sounds odd. Could you please provide more information as set out in the How To Get Support sticky? It'd help a lot in figuring out what's going wrong.

[jwt101]

Hi. I did use that thread as a basis for my question, but it is quite a general problem affecting flight physics. I will try again, but feel free to ask for anything specific that is missing.

What Happens: Craft descends extremely slowly at low altitutes (few 1,000m) in Kerbin atmosphere, when empty of fuel (zero thrust) and no parachute deployed. It descends tail-first extremely slowly through the last few thousand feet at <1m/s decent rate (oscillating between 0-5m/s), taking >5mins to pass the last 300m despite zero thrust. When the parachute is deployed decent rate increases immediately to a more normal 10m/s. Prior to chute deployment, if the craft is manually pointed nose-down the decent rate accelerates rapidly, which can be converted into a zoom-climb with no thrust.

Mods / Add-Ons: None

Steps to Replicate:

- Build a small rocket consisting of

a craft: Stayputnik, FL-T400 fuel tank, LV-T30 liquid fuel engine, large inertial stabiliser, 4 symetrically placed winglets, two battery packs and a parachute

a launcher: 4 solid fuel boosters in two stages

- launch, flying until all three stages have depleted of fuel (craft usually goes into an uncontrolled spin after pitching to 45 degrees during the second stage)

- Do not deploy parachute.

Result: Craft will descend rapidly until the last few 1000m, where it will slow almost to a standstill and descend slowly all the while it is orientated with the (dead) liquid engine pointing downwards.

Fixes/Workarounds: Point craft nose down to temporarily increase descent rate.

Other Notes/Pictures/Log Files: None

[Tex_NL]

Most likely you've just encountered the infamous infiniglide bug.

The stock atmosphere is extremely soupy and control surfaces don't work as you might expect. Control surfaces apply a force instead of redirecting airflow. The total amount of force can be enough to fly indefinitely. Even enough to escape Kerbins SOI.

[vexx32]

According to Maxmaps, at least, fixing the aerodynamics is a big part of the next update, so let's see what the future brings.